After her husband's sudden death, Shiori Tsukada, now a widow, lives alone with her stepson. Though not related by blood, the two had long harbored romantic feelings for each other even during her husband's lifetime, yet always restrained themselves from crossing the line. With her husband gone, the barrier between them vanishes, giving way to new, undeniable emotions. Seizing a hot spring trip as their chance, they make a firm decision to finally act on their desires.